Artificial leg



June 18, 1946. N. F. HARRINGTON ARTIFICIAL LEG Filed May 5, 1945 INVEN TOR. Rem/670M I M /Z I 14770E/VEX JVBEL 1% Patented June 18, 1946 UNITED STATES PATENT OFFICE My invention relates to artificial legs and has particular reference to an artificial leg which may be employed with either above the knee amputations or below the knee amputations.

Artificial legs which include a knee joint have been formed with the knee joint constructed as either a single bolt extending transversely through the knee joint about which the knee joint is to pivot or the knee joint has been formed of a pair of laterally spaced pivots, one on each side of the artificial leg to provide a pivotal action as near as possible to the center of pivotal action of the original human leg. All of these previous constructions have had the disadvantage that the knee joint pivot mechanism required a considerable mass of metal and metal and wood, adding excess weight to the knee joint which produced an inertia at the joint, prevent ing a natural freedom of action of the artificial leg.

Another disadvantage of such knee joints has been that the axis of the pivotal movement was disposed so near to the front of the leg as to render the leg unstable, particularly when the user was required to make a relatively high step.

It is therefore an object of my invention to provide an artificial leg structure in which the knee joint is disposed at the rear of the artificial leg to increase the stability of the leg.

Another object of my invention is to provide an artificial leg of the character described wherein the kne joint comprises a single lightweight hinge member disposed at the rear of the leg, the hinge pivoting about an axis disposed at the point of bending between the rear portion of the upper leg and the rear portion of the lower leg, the axis extending transversely of the leg to provide lateral stability.

Another object of my invention is to provide a structure of the character described particularly adapted for below knee amputations, in which the pivot between the upper leg portion and the lower leg portion of the artificial leg is employed for lateral stability while the motion between the upper and lower leg members is provided by the natural knee joint.

Other objects and advantage of my invention will be apparent from a study of the following specifications, read in connection with the accompanying drawing, wherein Fig. 1 is an elevational view of my artificial leg applied to a below the knee amputation with the leg in the standing position;

Fig. 2 is a view similar to Fig. 1 but illustrating the position of the artificial leg parts when the leg is in a bent position as when the wearer is sitting down;

3 is a vertical sectionalview of the artificial leg shown in Figs. 1 and 2;

Fig. 4 is a perspective view of a hinge employed between the upper and lower leg portions of the artificial leg shown in Figs, 1, 2 and 3; and

Fig.5 is a' longitudinal sectional view of the hinge joint illustrating a stop employed for limiting the hinge movement in one direction, taken along line V--V of Fig- 4.

Referring to the drawing,- I have illustrated in Fig. 1 my artificial leg as comprisinga lower leg member I and an upper leg member 2 intercon- 15 nected by a'single flat hinge member 3 to provide a hinging motion between the upper and lower leg members at the knee joint. I v

The particular form of artificial leg shown in Figs. 1, 2 and 3 is illustrated as being applied to at below the knee amputation wherein the lower leg'portion I i provided with a suitable internal socket 4 into which the stump 5 of the natural leg may be inserted while the upper leg portion may be formed as a harness adapted to be wound about the upper, portion of the natural leg and adjusted thereto as by means of lacinge 6.

With my artificial leg applied to this type of amputation, it will be apparent that the frictional engagement of the lower portion of the natural legwithin .the socket 4 will provide a sufficient engagement therebetween to support the weight of'the-lower leg portion" I so that the natural knee may be used to provide the knee joint action between the upper and lower artificial le members. However, as willbe understood, the artificial lower leg is subjected to. rotary twists as well as to lateral bending moments as the wearer walks upon the artificial leg and it is necessary to provide a stability between the upper and lower leg members to resist such twisting or lateral bending motion. This may be readily ac complished by means of the hinge member 3 which comprises in effect a strap hinge, the lower element 1 of which may comprise a plate adapted 45 to be secured to the lower leg member I as by means of screws 8. The upper end of the lower hinge element 1 is preferably rolled upon itself, as indicated at 9, to form alaterally extending cylindrica1 .bearing which permits the pivotal at- 50 tachment of an upper hinge element l0 thereto.

The central portion of the bearing of'the lower hinge element is preferably cut away so as to receive a similarly rolled end H of the upper hinge element In whereby a pair of short pivot 55 pins l2 and I3 may be threaded through the O hinge members 9 of the lower hinge element -1 and into conical sockets I4 formed in the bearing I I of the upper hinge element I0.

Where the artificial leg is to be used with the below the knee amputation, the upper hinge element Ill is preferably formed as an elongated strap of metal adapted to slide longitudinally of a box-like structure I5 secured as by means of rivets or other suitable securing mechanism to the rear of the upper leg memberor harness 2, the upper hinge element I being adapted to freely slide up and down within the box-like securing structure I limited only to motion be- 7 tween an extreme upper and an extremelower position as by means of a nm It secured:to-.-the

hinge element I0 and projecting through a vertically disposed slot I1 formed-in the rear-wallof the box structure I 5.

It will be noted that the single hinge 3 is secured at the rear of the upper and lower leg members I and 2 and may be constructedaof extremely light material, providing substantially little mass concentrated at the 'kneejoint while the engagement of the hinge with the upp r and lower leg members provides ample bracingto resist either a twisting motion between the upper and lower leg members-or lateral bending thrusts which would be imposed upon the natural knee joint. By permitting relative motion between the box structure I5 and the hinge, strap ID, the natural leg of the user'is-permittedto pivot around the natural knee joint without anyinterference with the hinge/employed on the 'artificial leg, any bending of'the' upper and lower leg members resulting in the retraction ofthe strap IEI into the box-like structure I5 a illustrated particularly-in- Fig. 2.

Thus for below'the knee amputations the artificial leg provides all of the support-which is required with a minimum of artificial weight added to the natural leg and natural knee joint.

The essentials of this structure are equallyadapted to above the knee amputations merely by omitting the slot I1 and securing the strap I0 either directly to the-upper leg harness:2 or by omitting the slot I 'I andsecuringthe strap I0 within the box-like structure-by the use of thepin I6 extending 'throughba circular opening.

formed in the'wall ofthe box structure I5' having a diameter equal to the diameter ofthe pin.

With such structure the artificialleg, which 'in eludes both the upper' leg .portion'and the lower leg portion hinged togetheriby the hinge 3, 'pro-,

vides all of'the stability against twisting as well as lateral bending and atthe same time provides a flexible hinge between'these members, permitting the support ofweight through the hinge.

When the device is adapted to" either type of amputation, it 'is desirable to provide a. stop,.

limiting the forward movement of the lower'leg portion I in its hinging movement which" may be readily provided by striking out a portion'of the metal of the hinge element II], as indicated at I8, and forming'up on the lower hinge element 1 a hook-like projection I9, the: end of which projects overv the end 2001 the mid portionof the upper hinge element .ID, as indicated in. Figs; 4 and 5 so that as-the lower leg is swung for wardly to a position of alignment withthe upper leg portion the hook I9 will engage the hinge element I0 and prevent further forward movement of the lower leg portion. If desired, a block 2| of fiber, rubber or other cushioning material may be secured on the end of the hook member I9 to act as a shock absorber, preventing unpleasant shocks to the wearer when the lower leg portion i brought to a stop.

In assembling the lower leg member I and the upper legharness-Z, I prefer to mount the harness upon the upper portion of the natural leg and then to dispose the lower leg member I in correct aligned position with the upper leg prior to the attachment of the hinge 3 to the lower leg membersothat-upon securing the hinge to the lower engage the conical sockets I4, it will be apparent that any amount of ivotal adjustment of the hinge members may be-readily accomplished to insure against undue friction or undue lost motion between the upper and'lower leg members.

It will'be understood from the foregoing description and the drawing that any suitable ankle structure may be employed but for the purpose of the foregoing description it is not deemed necessary to illustrate or describe such structure in any detail.

It will be apparent from'the' foregoing that an artificialleg constructed in accordance-with my invention provides a sufiicientsupport/against twisting and lateral movements between the upper and lower leg elements with a minimum of weight required in theknee joint. In additiomit will be noted thatthe'dispositionof the hinge at' the rear of the leg places the hinge action 'at'a point at which the leg naturally tends to straighten out to align the upper and lower leg members While at the same time such disposition of the hinge leaves the knee" free for bending movements without irritatingconstrictions such' as accompany knee joints having pivotal hinges disposedat'thesides of the knee.

While I have shown and describedthe'preferred embodiment or'my'invention, I do not desire" to be limited to any ofthe detailsofconstruction shown or described herein, except as defined in the appended claim:

In an'artificial leg; a lower leg member'defining an artificial lower leg, ankl'e'andfootto'be disposed below the position. of a natural knee of the wearer, an upper-leg harness adapted to surround a portion of theuppernatural leg, a single strap hinge disposed at the rear. of saidharness and said leg member, the pivot of the hingegbeing disposed in alignment with the naturaliknee joint and extending transversely of thelower leg. joint, said strap hinge comprisinga lower hinge element adapted to be secured tothe lower leg.

member, an upper hinge element, a box=likel structure secured to the upper legharnesstfor slidably receiving said upper hinge element,. and.

NOEL; HARRINGTON: 

